Bump version 12.0.1.2.6

CHANGELOG:

## [12.0.1.2.6] - 2021-05-21
### Fixed
- [#513](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/513) Fix remesa crm lead lines adding validation error
- [#511](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/511) Payment return match button account.move.lines now uses 'like' for reference instead of '='
- [#506](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/506) Convert the service "previous_owner_vat_number" with an actual VAT format.
- [#501](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/501) Save VAT from partner with create SR from partner wizard
- [#478](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/478) Remove duplicated request in terminate contract process
- [#441](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/441) Fixed domain to include `general` type journals in account return import

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